The present invention relates generally to a clamping device, and more particularly, to a flexible, encircling, clamping apparatus of the worm gear type.
Worm gear clamping devices, such as those disclosed in U.S. Pat. Nos. 3,371,392 and 3,521,334, are widely used because they offer certain advantages over spring-type clamping devices or other types of clamping devices which are applicable to only a relatively narrow range of diameters. For example, worm gear clamping devices are more convenient to use, do not require special tools for installation and removal, and allow adjustment of the clamping forces.
However, the prior art worm gear clamping devices also involve some disadvantages. One of the problems arising with the use of the early worm gear clamping devices has been corrosion, because these devices have usually utilized metal components, and any such corrosion interferes with the removal of the clamping device. More recently, worm gear clamping devices have utilized molded plastic components; see, for example, the clamping device disclosed in U.S. Pat. No. 3,914,832, assigned to the assignee of the present invention. Therefore, although it will become apparent subsequently that the clamping device of the present invention may utilize metal components, the invention advantaeously uses molded plastic components, and will be described as such.
A common disadvantage of the prior art worm gear clamping devices is that they have generally been too complicated, too difficult to assemble, or both. By difficult to assemble, it is meant that with most such devices it has been necessary to insert the free end of the strap into the worm gear drive head, and into engagement with the worm member and from there, reduce the diameter of the clamping device all the way to the point where it begins to clamp by turning the worm member, such as by means of a screwdriver or wrench. It will be apparent that the time required to thread a substantial length of the strap through the worm gear drive head by turning the worm member may prevent the use of such clamping devices from being economically feasible where a large number of such installation operations are required.
One alternative to eliminate the need for threading a long length of the strap is to fabricate the clamping device with a larger variety of strap lengths, which inroduces additional expense and/or inventory problems.